Re: [PATCH 2/2] power: supply: qcom_battmgr: expose CHARGE_NOW on SM8350-class firmware

[Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>]

On 9/2/26 5:02 PM, Konrad Dybcio wrote:
> On 8/29/26 7:45 AM, Jan-Michael Brummer wrote:
>> The SM8350-class firmware does not implement a dedicated 'charge now'
>> property. It does however report BATT_CHG_COUNTER, and on this class of
>> firmware that value is the remaining charge in uAh rather than a
>> monotonic counter. Measured on a Fairphone 5 with charge_full at
>> 4116000 uAh:
>>
>>   BATT_CHG_COUNTER   reported capacity   counter / charge_full
>>   2434614            59%                 59.1%
>>   3525354            85%                 85.6%
>>
>> Map POWER_SUPPLY_PROP_CHARGE_NOW onto the same firmware property and
>> store the value in status.capacity, which the CHARGE_NOW/ENERGY_NOW case
>> of qcom_battmgr_bat_get_property() already reads.
>>
>> Together with the preceding patch this gives userspace both the full
>> charge and the current charge. UPower now derives an energy level and
>> runtime estimates in both directions:
>>
>>     state:               discharging      state:               charging
>>     energy:              14.4347 Wh       energy:              15.6003 Wh
>>     energy-full:         16.8807 Wh       energy-full:         18.1505 Wh
>>     energy-rate:         3.39313 W        energy-rate:         7.3492 W
>>     time to empty:       4.3 hours        time to full:        20.8 minutes
>>
>> Signed-off-by: Jan-Michael Brummer <jan.brummer@tabos.org>
>> ---
> 
> Ok this makes more sense now. We should still gate the other property though.
> 
> [...]
> 
>> @@ -1442,7 +1445,10 @@ static void qcom_battmgr_sm8350_callback(struct qcom_battmgr *battmgr,
>>  			battmgr->info.technology = le32_to_cpu(resp->intval.value);
>>  			break;
>>  		case BATT_CHG_COUNTER:
>> -			battmgr->info.charge_count = le32_to_cpu(resp->intval.value);
>> +			val = le32_to_cpu(resp->intval.value);
>> +			battmgr->info.charge_count = val;
>> +			/* the firmware reports the remaining charge here */
>> +			battmgr->status.capacity = val;
> 
> Let me try and find whether we can rely on this - on newer targets
> many properties are more or less just front-ends for vendor
> plumbing (because there's a ton of different chargers etc.)

There's a comment saying /* remaining capacity in uAh */, so it seems
like this should be OK

Konrad